1. Field of the Invention
The present invention generally relates to a method for determining the type of a disk, and more particularly, to a method for determining the type of a blu-ray disk and an optical storage apparatus thereof.
2. Description of Related Art
With the rapid development of blu-ray storage technology, the price of a blu-ray disk (BD) is gradually reduced. However, it is still more expensive than a digital versatile disc (DVD), which is currently the mainstream in the market. For this reason, a new method called “Low to High (LTH)” related to a format standard, BD-R Format V1.2, for blu-ray has been developed, and it's helpful to reduce the cost of the BD.
The disks use the LTH method are coated with organic compounds, i.e. organic dyes, as a data layer. The LTH method is related to a method for recording data, in which the reflectivity of regions of writing data changes from low to high. Accordingly, a disk, which data is written with the LTH technology, is an LTH disk.
FIG. 1 is a diagram of a blu-ray disk. Referring to FIG. 1, regions for writing data are called “MARK”, and regions not for writing data are called “SPACE”. In the LTH disk, after the data is written, the reflectivity of the MARK regions is raised and is much higher than the reflectivity of the SPACE regions not for writing data. Since the reflectivity of the MARK regions is raised from low to high, the disk is the LTH disk.
The conventional blu-ray disks are coated with metal compounds, i.e. inorganic dyes, as the data layer. Accordingly, a disk, which data is written with the HTL method, is an HTL disk. In the HTL disk, after the data is written, the reflectivity of the regions for writing data changes from high to low. That is, the reflectivity of the MARK regions changes from high to low. At present, the blue-ray re-writeable disks (BD-RWs) are generally HTL type. Accordingly, when the LTH disk is read by a reading/writing system of an optical disk drive, the optical disk drive has to load a specific judging mechanism with a suitable setting and a specific servo operation.
Since the reflectivities of the regions for writing data are much different between the LTH disk and the HTL disk, the optical disk drive must have to first determine the type of the disk in order to correctly play and record the disk. Next, according to the type of the disk, parameters for servo signals, such as a tracking error (TE) signal and a focus error (FE) signal, are optimal set. In order to ensure the quality of the signals on disk, the parameters, such as gains, for the above-described servo signals have to be regulated due to the type of the disk. Furthermore, since the reflectivities are different due to the types of the disks, intensity of radio frequency (RF) signals, i.e. data signals, are also different. As a result, the parameters for an RF equalizer (RF EQ) and the laser power for the optical pick-up head have to be modified according to the types of the disks.